Internet Engineering Task Force (IETF)                          S. Salam
Request for Comments: 9062                                    A. Sajassi
Category: Informational                                            Cisco
ISSN: 2070-1721                                                S. Aldrin
                                                                  Google
                                                                J. Drake
                                                                 Juniper
                                                         D. Eastlake 3rd
                                                               Futurewei
                                                               June 2021


           Framework and Requirements for Ethernet VPN (EVPN)
           Operations, Administration, and Maintenance (OAM)

Abstract

   This document specifies the requirements and reference framework for
   Ethernet VPN (EVPN) Operations, Administration, and Maintenance
   (OAM).  The requirements cover the OAM aspects of EVPN and Provider
   Backbone Bridge EVPN (PBB-EVPN).  The framework defines the layered
   OAM model encompassing the EVPN service layer, network layer,
   underlying Packet Switched Network (PSN) transport layer, and link
   layer but focuses on the service and network layers.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are candidates for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9062.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
     1.1.  Relationship to Other OAM Work
     1.2.  Specification of Requirements
     1.3.  Terminology
   2.  EVPN OAM Framework
     2.1.  OAM Layering
     2.2.  EVPN Service OAM
     2.3.  EVPN Network OAM
     2.4.  Transport OAM for EVPN
     2.5.  Link OAM
     2.6.  OAM Interworking
   3.  EVPN OAM Requirements
     3.1.  Fault Management Requirements
       3.1.1.  Proactive Fault Management Functions
         3.1.1.1.  Fault Detection (Continuity Check)
         3.1.1.2.  Defect Indication
           3.1.1.2.1.  Forward Defect Indication (FDI)
           3.1.1.2.2.  Reverse Defect Indication (RDI)
       3.1.2.  On-Demand Fault Management Functions
         3.1.2.1.  Connectivity Verification
         3.1.2.2.  Fault Isolation
     3.2.  Performance Management
       3.2.1.  Packet Loss
       3.2.2.  Packet Delay and Jitter
   4.  Security Considerations
   5.  IANA Considerations
   6.  References
     6.1.  Normative References
     6.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   This document specifies the requirements and defines a reference
   framework for Ethernet VPN (EVPN) Operations, Administration, and
   Maintenance (OAM) [RFC6291].  In this context, we use the term "EVPN
   OAM" to loosely refer to the OAM functions required for and/or
   applicable to [RFC7432] and [RFC7623].

   EVPN is a Layer 2 VPN (L2VPN) solution for multipoint Ethernet
   services with advanced multihoming capabilities that uses BGP for
   distributing Customer/Client Media Access Control (C-MAC) address
   reachability information over the core MPLS/IP network.

   PBB-EVPN combines Provider Backbone Bridging (PBB) [IEEE-802.1Q] with
   EVPN in order to reduce the number of BGP MAC advertisement routes;
   provide client MAC address mobility using C-MAC [RFC7623] aggregation
   and Backbone MAC (B-MAC) [RFC7623] sub-netting; confine the scope of
   C-MAC learning to only active flows; offer per-site policies; and
   avoid C-MAC address flushing on topology changes.

   This document focuses on the fault management and performance
   management aspects of EVPN OAM.  It defines the layered OAM model
   encompassing the EVPN service layer, network layer, underlying Packet
   Switched Network (PSN) transport layer, and link layer but focuses on
   the service and network layers.

1.1.  Relationship to Other OAM Work

   This document leverages concepts and draws upon elements defined
   and/or used in the following documents:

   [RFC6136] specifies the requirements and a reference model for OAM as
   it relates to L2VPN services, pseudowires, and associated Packet
   Switched Network (PSN) tunnels.  This document focuses on Virtual
   Private LAN Service (VPLS) and Virtual Private Wire Service (VPWS)
   solutions and services.

   [RFC8029] defines mechanisms for detecting data plane failures in
   MPLS Label Switched Paths (LSPs), including procedures to check the
   correct operation of the data plane as well as mechanisms to verify
   the data plane against the control plane.

   [IEEE-802.1Q] specifies the Ethernet Connectivity Fault Management
   (CFM) protocol, which defines the concepts of Maintenance Domains,
   Maintenance Associations, Maintenance End Points, and Maintenance
   Intermediate Points.

   [Y.1731] extends Connectivity Fault Management in the following
   areas: it defines fault notification and alarm suppression functions
   for Ethernet and specifies mechanisms for Ethernet performance
   management, including loss, delay, jitter, and throughput
   measurement.

1.2.  Specification of Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.3.  Terminology

   This document uses the following terminology, much of which is
   defined in [RFC6136]:

   CE          Customer Edge device; for example, a host, router, or
               switch.

   CFM         Connectivity Fault Management [IEEE-802.1Q]

   DF          Designated Forwarder [RFC7432]

   Down MEP    A MEP that originates traffic away from and terminates
               traffic towards the core of the device in whose port it
               is logically located.

   EVI         An EVPN instance spanning the Provider Edge (PE) devices
               participating in that EVPN [RFC7432].

   L2VPN       Layer 2 VPN

   LOC         Loss of continuity

   MA          Maintenance Association; a set of MEPs belonging to the
               same Maintenance Domain (MD) established to verify the
               integrity of a single service instance [IEEE-802.1Q].

   MD          Maintenance Domain; an OAM Domain that represents a
               region over which OAM frames can operate unobstructed
               [IEEE-802.1Q].

   MEP         Maintenance End Point; it is responsible for origination
               and termination of OAM frames for a given MA.  A MEP is
               logically located in a device's port [IEEE-802.1Q].

   MIP         Maintenance Intermediate Point; it is located between
               peer MEPs and can process and respond to certain OAM
               frames but does not initiate them.  A MIP is logically
               located in a device's port [IEEE-802.1Q].

   MP2P        Multipoint to Point

   NMS         Network Management Station [RFC6632]

   P           Provider network interior (non-edge) node

   P2MP        Point to Multipoint

   PBB         Provider Backbone Bridge [RFC7623]

   PE          Provider Edge network device

   Up MEP      A MEP that originates traffic towards and terminates
               traffic from the core of the device in whose port it is
               logically located.

   VPN         Virtual Private Network

2.  EVPN OAM Framework

2.1.  OAM Layering

   Multiple layers come into play for implementing an L2VPN service
   using the EVPN family of solutions as listed below.  The focus of
   this document is the service and network layers.

   *  The service layer runs end to end between the sites or Ethernet
      segments that are being interconnected by the EVPN solution.

   *  The network layer extends between the EVPN PE (Provider Edge)
      nodes and is mostly transparent to the P (provider network
      interior) nodes (except where flow entropy comes into play).  It
      leverages MPLS for service (i.e., EVI) multiplexing and split-
      horizon functions.

   *  The transport layer is dictated by the networking technology of
      the PSN.  It may be based on either MPLS LSPs or IP.

   *  The link layer is dependent upon the physical technology used.
      Ethernet is a popular choice for this layer, but other
      alternatives are deployed (e.g., Packet over SONET (POS), Dense
      Wavelength Division Multiplexing (DWDM), etc.).

   This layering extends to the set of OAM protocols that are involved
   in the ongoing maintenance and diagnostics of EVPN networks.
   Figure 1 below depicts the OAM layering and shows which devices have
   visibility into what OAM layer(s).

           +---+                               +---+
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
   |CE|----|PE |----| P |----| P |----| P |----|PE |----|CE|
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
           +---+                               +---+

     o-------o----------- Service OAM -----------o-------o

             o----------- Network OAM -----------o

             o--------o--------o--------o--------o  Transport OAM

      o----o   o----o   o----o   o----o   o----o   o----o  Link OAM

                           Figure 1: OAM Layering

   Service OAM and Network OAM mechanisms only have visibility to the PE
   nodes but not the P nodes.  As such, they can be used to deduce
   whether the fault is in the customer's own network, the local CE-PE
   segment, the PE-PE segment, or the remote CE-PE segment(s).  EVPN
   Transport OAM mechanisms can be used for fault isolation between the
   PEs and P nodes.

   Figure 2 below shows an example network where Ethernet domains are
   interconnected via EVPN using MPLS, and it shows the OAM mechanisms
   that are applicable at each layer.  The details of the layers are
   described in the sections below.

           +---+                               +---+
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
   |CE|----|PE |----| P |----| P |----| P |----|PE |----|CE|
   +--+    |   |    +---+    +---+    +---+    |   |    +--+
           +---+                               +---+

      o----o---------- CFM (Service OAM) ----------o----o

             o-------- EVPN Network OAM ---------o

             o--------o--------o--------o--------o MPLS OAM

      o----o   o----o   o----o   o----o   o----o   o----o 802.3 OAM
                                                          [IEEE-802.3]

                         Figure 2: EVPN OAM Example

2.2.  EVPN Service OAM

   The EVPN Service OAM protocol depends on what service-layer
   technology is being interconnected by the EVPN solution.  In the case
   of [RFC7432] and [RFC7623], the service layer is Ethernet; hence, the
   corresponding Service OAM protocol is Ethernet CFM [IEEE-802.1Q].

   EVPN Service OAM is visible to the CEs and EVPN PEs but not to the P
   nodes.  This is because the PEs operate at the Ethernet MAC layer in
   [RFC7432] and [RFC7623], whereas the P nodes do not.

   The EVPN PE MUST support MIP functions in the applicable Service OAM
   protocol (for example, Ethernet CFM).  The EVPN PE SHOULD support MEP
   functions in the applicable Service OAM protocol.  This includes both
   Up and Down MEP functions.

   As shown in Figure 3, the MIP and MEP functions being referred to are
   logically located within the device's port operating at the customer
   level.  (There could be MEPs/MIPs within PE ports facing the provider
   network, but they would not be relevant to EVPN Service OAM as the
   traffic passing through them will be encapsulated/tunneled, so any
   customer-level OAM messages will just be treated as data.)  Down MEP
   functions are away from the core of the device while Up MEP functions
   are towards the core of the device (towards the PE forwarding
   mechanism in the case of a PE).  OAM messages between the PE Up MEPs
   shown are a type of EVPN Network OAM, while such messages between the
   CEs or from a PE to its local CE or to the remote CE are Service
   OAMs.

    +-------+   +----------------+       +----------------+   +-------+
    |+-----+|   |+--------------+|       |+--------------+|   |+-----+|
    ||  CE ||   ||     PE       ||  ...  ||       PE     ||   || CE  ||
    |+--+--+|   |+---+--------+-+|       |+-+--------+---+|   |+--+--+|
    |   |   |   |    |        |  |       |  |        |    |   |   |   |
    |+--+--+|   |+---+-----+  .  |       |  .  +-----+---+|   |+--+--+|
    || MEP ||   ||   | Up ^|  .  |  ...  |  .  | Up ^|   ||   || MEP ||
    ||DownV||   ||MIP|MEP  |  .  |       |  .  |MEP  |MIP||   ||DownV||
    |+--+--+|   ||   |DownV|  .  |       |  .  |DownV|   ||   |+--+--+|
    |   |   |   |+---+-----+  |  |       |  |  +-----+---+|   |   |   |
    +---|---+   +----|--------|--+       +--|--------|----+   +---|---+
        |            |        |             |        |            |
        +------------+        +---  ...  ---+        +------------+

                           Figure 3: CFM Details

   The EVPN PE MUST, by default, learn the MAC address of locally
   attached CE MEPs by snooping on CFM frames and advertising them to
   remote PEs as a MAC/IP Advertisement route.  Some means to limit the
   number of MAC addresses that a PE will learn SHOULD be implemented.

   The EVPN PE SHOULD advertise any MEP/MIP local to the PE as a MAC/IP
   Advertisement route.  Since these are not subject to mobility, they
   SHOULD be advertised with the static (sticky) bit set (see
   Section 15.2 of [RFC7432]).

2.3.  EVPN Network OAM

   EVPN Network OAM is visible to the PE nodes only.  This OAM layer is
   analogous to Virtual Circuit Connectivity Verification (VCCV)
   [RFC5085] in the case of VPLS/VPWS.  It provides mechanisms to check
   the correct operation of the data plane as well as a mechanism to
   verify the data plane against the control plane.  This includes the
   ability to perform fault detection and diagnostics on:

   *  the MP2P tunnels used for the transport of unicast traffic between
      PEs.  EVPN allows for three different models of unicast label
      assignment: label per EVI, label per <ESI, Ethernet Tag>, and
      label per MAC address.  In all three models, the label is bound to
      an EVPN Unicast Forwarding Equivalence Class (FEC).  EVPN Network
      OAM MUST provide mechanisms to check the operation of the data
      plane and verify that operation against the control plane view.

   *  the MP2P tunnels used for aliasing unicast traffic destined to a
      multihomed Ethernet segment.  The three label assignment models,
      discussed above, apply here as well.  In all three models, the
      label is bound to an EVPN Aliasing FEC.  EVPN Network OAM MUST
      provide mechanisms to check the operation of the data plane and
      verify that operation against the control plane view.

   *  the multicast tunnels (either MP2P or P2MP) used for the transport
      of broadcast, unknown unicast, and multicast traffic between PEs.
      In the case of ingress replication, a label is allocated per EVI
      or per <EVI, Ethernet Tag> and is bound to an EVPN Multicast FEC.
      In the case of Label Switched Multicast (LSM) and, more
      specifically, aggregate inclusive trees, again, a label may be
      allocated per EVI or per <EVI, Ethernet Tag> and is bound to the
      tunnel FEC.

   *  the correct operation of the Ethernet Segment Identifier (ESI)
      split-horizon filtering function.  In EVPN, a label is allocated
      per multihomed Ethernet segment for the purpose of performing the
      access split-horizon enforcement.  The label is bound to an EVPN
      Ethernet segment.

   *  the correct operation of the Designated Forwarder (DF) [RFC7432]
      filtering function.  EVPN Network OAM MUST provide mechanisms to
      check the operation of the data plane and verify that operation
      against the control plane view for the DF filtering function.

   EVPN Network OAM mechanisms MUST provide in-band monitoring
   capabilities.  It is desirable, to the extent practical, for OAM test
   messages to share fate with data messages.  Details of how to achieve
   this are beyond the scope of this document.

   EVPN Network OAM SHOULD provide both proactive and on-demand
   mechanisms of monitoring the data plane operation and data plane
   conformance to the state of the control plane.

2.4.  Transport OAM for EVPN

   The Transport OAM protocol depends on the nature of the underlying
   transport technology in the PSN.  MPLS OAM mechanisms [RFC8029]
   [RFC6425] as well as ICMP [RFC0792] and ICMPv6 [RFC4443] are
   applicable, depending on whether the PSN employs MPLS or IP
   transport, respectively.  Furthermore, Bidirectional Forwarding
   Detection (BFD) mechanisms per [RFC5880], [RFC5881], [RFC5883], and
   [RFC5884] apply.  Also, the BFD mechanisms pertaining to MPLS-TP LSPs
   per [RFC6428] are applicable.

2.5.  Link OAM

   Link OAM depends on the data-link technology being used between the
   PE and P nodes.  For example, if Ethernet links are employed, then
   Ethernet Link OAM ([IEEE-802.3], Clause 57) may be used.

2.6.  OAM Interworking

   When interworking two networking domains, such as actual Ethernet and
   EVPN to provide an end-to-end emulated service, there is a need to
   identify the failure domain and location, even when a PE supports
   both the Service OAM mechanisms and the EVPN Network OAM mechanisms.
   In addition, scalability constraints may not allow the running of
   proactive monitoring, such as Ethernet Continuity Check Messages
   (CCMs) [IEEE-802.1Q], at a PE to detect the failure of an EVI across
   the EVPN domain.  Thus, the mapping of alarms generated upon failure
   detection in one domain (e.g., actual Ethernet or EVPN network
   domain) to the other domain is needed.  There are also cases where a
   PE may not be able to process Service OAM messages received from a
   remote PE over the PSN even when such messages are defined, as in the
   Ethernet case, thereby necessitating support for fault notification
   message mapping between the EVPN Network domain and the Service
   domain.

   OAM interworking is not limited, though, to scenarios involving
   disparate network domains.  It is possible to perform OAM
   interworking across different layers in the same network domain.  In
   general, alarms generated within an OAM layer, as a result of
   proactive fault detection mechanisms, may be injected into its
   client-layer OAM mechanisms.  This allows the client-layer OAM to
   trigger event-driven (i.e., asynchronous) fault notifications.  For
   example, alarms generated by the Link OAM mechanisms may be injected
   into the Transport OAM layer, and alarms generated by the Transport
   OAM mechanism may be injected into the Network OAM mechanism, and so
   on.

   EVPN OAM MUST support interworking between the Network OAM and
   Service OAM mechanisms.  EVPN OAM MAY support interworking among
   other OAM layers.

3.  EVPN OAM Requirements

   This section discusses the EVPN OAM requirements pertaining to fault
   management and performance management.

3.1.  Fault Management Requirements

3.1.1.  Proactive Fault Management Functions

   The network operator configures proactive fault management functions
   to run periodically.  Certain actions (for example, protection
   switchover or alarm indication signaling) can be associated with
   specific events, such as entering or clearing fault states.

3.1.1.1.  Fault Detection (Continuity Check)

   Proactive fault detection is performed by periodically monitoring the
   reachability between service end points, i.e., MEPs in a given MA,
   through the exchange of CCMs [IEEE-802.1Q].  The reachability between
   any two arbitrary MEPs may be monitored for:

   *  in-band, per-flow monitoring.  This enables per-flow monitoring
      between MEPs.  EVPN Network OAM MUST support fault detection with
      per-user flow granularity.  EVPN Service OAM MAY support fault
      detection with per-user flow granularity.

   *  a representative path.  This enables a liveness check of the nodes
      hosting the MEPs, assuming that the loss of continuity (LOC) to
      the MEP is interpreted as a failure of the hosting node.  This,
      however, does not conclusively indicate liveness of the path(s)
      taken by user data traffic.  This enables node failure detection
      but not path failure detection through the use of a test flow.
      EVPN Network OAM and Service OAM MUST support fault detection
      using test flows.

   *  all paths.  For MPLS/IP networks with ECMP, the monitoring of all
      unicast paths between MEPs (on non-adjacent nodes) may not be
      possible since the per-hop ECMP hashing behavior may yield
      situations where it is impossible for a MEP to pick flow entropy
      characteristics that result in exercising the exhaustive set of
      ECMP paths.  The monitoring of all ECMP paths between MEPs (on
      non-adjacent nodes) is not a requirement for EVPN OAM.

   The fact that MPLS/IP networks do not enforce congruency between
   unicast and multicast paths means that the proactive fault detection
   mechanisms for EVPN networks MUST provide procedures to monitor the
   unicast paths independently of the multicast paths.  This applies to
   EVPN Service OAM and Network OAM.

3.1.1.2.  Defect Indication

   Defect indications can be categorized into two types: forward and
   reverse, as described below.  EVPN Service OAM MUST support at least
   one of these types of event-driven defect indications upon the
   detection of a connectivity defect.

3.1.1.2.1.  Forward Defect Indication (FDI)

   FDI is used to signal a failure that is detected by a lower-layer OAM
   mechanism.  A server MEP (i.e., an actual or virtual MEP) transmits a
   forward defect indication in a direction away from the direction of
   the failure (refer to Figure 4 below).

                              Failure
                                 |
          +-----+      +-----+   V   +-----+      +-----+
          |  A  |------|  B  |--XXX--|  C  |------|  D  |
          +-----+      +-----+       +-----+      +-----+

              <===========|             |============>
                Forward                    Forward
                Defect                     Defect
                Indication                 Indication

                    Figure 4: Forward Defect Indication

   Forward defect indication may be used for alarm suppression and/or
   for the purpose of interworking with other layer OAM protocols.
   Alarm suppression is useful when a transport-level or network-level
   fault translates to multiple service- or flow-level faults.  In such
   a scenario, it is enough to alert a network management station (NMS)
   of the single transport-level or network-level fault in lieu of
   flooding that NMS with a multitude of Service or Flow granularity
   alarms.  EVPN PEs SHOULD support forward defect indication in the
   Service OAM mechanisms.

3.1.1.2.2.  Reverse Defect Indication (RDI)

   RDI is used to signal that the advertising MEP has detected a LOC
   defect.  RDI is transmitted in the direction of the failure (refer to
   Figure 5).

                              Failure
                                 |
          +-----+      +-----+   V   +-----+      +-----+
          |  A  |------|  B  |--XXX--|  C  |------|  D  |
          +-----+      +-----+       +-----+      +-----+

              |===========>             <============|
                Reverse                    Reverse
                Defect                     Defect
                Indication                 Indication

                    Figure 5: Reverse Defect Indication

   RDI allows single-sided management, where the network operator can
   examine the state of a single MEP and deduce the overall health of a
   monitored service.  EVPN PEs SHOULD support reverse defect indication
   in the Service OAM mechanisms.  This includes both the ability to
   signal a LOC defect to a remote MEP as well as the ability to
   recognize RDI from a remote MEP.  Note that, in a multipoint MA, RDI
   is not a useful indicator of unidirectional fault.  This is because
   RDI carries no indication of the affected MEP(s) with which the
   sender had detected a LOC defect.

3.1.2.  On-Demand Fault Management Functions

   On-demand fault management functions are initiated manually by the
   network operator and continue for a bounded time period.  These
   functions enable the operator to run diagnostics to investigate a
   defect condition.

3.1.2.1.  Connectivity Verification

   EVPN Network OAM MUST support on-demand connectivity verification
   mechanisms for unicast and multicast destinations.  The connectivity
   verification mechanisms SHOULD provide a means for specifying and
   carrying the following in the messages:

   *  variable-length payload/padding to test connectivity problems
      related to the Maximum Transmission Unit (MTU).

   *  test frame formats as defined in Appendix C of [RFC2544] to detect
      potential packet corruption.

   EVPN Network OAM MUST support connectivity verification at per-flow
   granularity.  This includes both user flows (to test a specific path
   between PEs) as well as test flows (to test a representative path
   between PEs).

   EVPN Service OAM MUST support connectivity verification on test flows
   and MAY support connectivity verification on user flows.

   For multicast connectivity verification, EVPN Network OAM MUST
   support reporting on:

   *  the DF filtering status of a specific port(s) or all the ports in
      a given bridge domain.

   *  the split-horizon filtering status of a specific port(s) or all
      the ports in a given bridge domain.

3.1.2.2.  Fault Isolation

   EVPN OAM MUST support an on-demand fault localization function.  This
   involves the capability to narrow down the locality of a fault to a
   particular port, link, or node.  The characteristic of forward/
   reverse path asymmetry in MPLS/IP makes fault isolation a direction-
   sensitive operation.  That is, given two PEs A and B, localization of
   continuity failures between them requires running fault-isolation
   procedures from PE A to PE B as well as from PE B to PE A.

   EVPN Service OAM mechanisms only have visibility to the PEs but not
   the MPLS or IP P nodes.  As such, they can be used to deduce whether
   the fault is in the customer's own network, the local CE-PE segment,
   or a remote CE-PE segment(s).  EVPN Network and Transport OAM
   mechanisms can be used for fault isolation between the PEs and P
   nodes.

3.2.  Performance Management

   Performance management functions can be performed both proactively
   and on demand.  Proactive management involves a recurring function,
   where the performance management probes are run continuously without
   a trigger.  We cover both proactive and on-demand functions in this
   section.

3.2.1.  Packet Loss

   EVPN Network OAM SHOULD provide mechanisms for measuring packet loss
   for a given service -- for example, [RFC7680] and [RFC6673].

   Given that EVPN provides inherent support for multipoint-to-
   multipoint connectivity, packet loss cannot be accurately measured by
   means of counting user data packets.  This is because user packets
   can be delivered to more PEs or more ports than are necessary (e.g.,
   due to broadcast, unpruned multicast, or unknown unicast flooding).
   As such, a statistical means of approximating the packet loss rate is
   required.  This can be achieved by sending "synthetic" OAM packets
   that are counted only by those ports (MEPs) that are required to
   receive them.  This provides a statistical approximation of the
   number of data frames lost, even with multipoint-to-multipoint
   connectivity.

3.2.2.  Packet Delay and Jitter

   EVPN Service OAM SHOULD support measurement of one-way and two-way
   packet delay and delay variation (jitter) across the EVPN network.
   Measurement of one-way delay requires clock synchronization between
   the probe source and target devices.  Mechanisms for clock
   synchronization are outside the scope of this document.  Note that
   Service OAM performance management mechanisms defined in [Y.1731] can
   be used.  See also [RFC7679], [RFC2681], and [RFC3393].

   EVPN Network OAM MAY support measurement of one-way and two-way
   packet delay and delay variation (jitter) across the EVPN network.

4.  Security Considerations

   EVPN OAM MUST prevent OAM packets from leaking outside of the EVPN
   network or outside their corresponding Maintenance Domain.  This can
   be done for CFM, for example, by having MEPs implement a filtering
   function based on the Maintenance Level associated with received OAM
   packets.

   EVPN OAM SHOULD provide mechanisms for implementation and optional
   use to:

   *  prevent denial-of-service attacks caused by exploitation of the
      OAM message channel (for example, by forging messages to exceed a
      Maintenance End Point's capacity to maintain state).

   *  authenticate communicating end points (for example, MEPs and
      MIPs).

5.  IANA Considerations

   This document has no IANA actions.

6.  References

6.1.  Normative References

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,
              <https://www.rfc-editor.org/info/rfc792>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/info/rfc4443>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
              DOI 10.17487/RFC5881, June 2010,
              <https://www.rfc-editor.org/info/rfc5881>.

   [RFC5883]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
              June 2010, <https://www.rfc-editor.org/info/rfc5883>.

   [RFC5884]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
              "Bidirectional Forwarding Detection (BFD) for MPLS Label
              Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
              June 2010, <https://www.rfc-editor.org/info/rfc5884>.

   [RFC6291]  Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
              D., and S. Mansfield, "Guidelines for the Use of the "OAM"
              Acronym in the IETF", BCP 161, RFC 6291,
              DOI 10.17487/RFC6291, June 2011,
              <https://www.rfc-editor.org/info/rfc6291>.

   [RFC6425]  Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
              Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
              Failures in Point-to-Multipoint MPLS - Extensions to LSP
              Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
              <https://www.rfc-editor.org/info/rfc6425>.

   [RFC6428]  Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed.,
              "Proactive Connectivity Verification, Continuity Check,
              and Remote Defect Indication for the MPLS Transport
              Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011,
              <https://www.rfc-editor.org/info/rfc6428>.

   [RFC7432]  Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
              Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
              Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
              2015, <https://www.rfc-editor.org/info/rfc7432>.

   [RFC7623]  Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W.
              Henderickx, "Provider Backbone Bridging Combined with
              Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623,
              September 2015, <https://www.rfc-editor.org/info/rfc7623>.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
              Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029,
              DOI 10.17487/RFC8029, March 2017,
              <https://www.rfc-editor.org/info/rfc8029>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

6.2.  Informative References

   [IEEE-802.1Q]
              IEEE, "IEEE Standard for Local and metropolitan area
              networks--Bridges and Bridged Networks", IEEE Std 802.1Q-
              2014, DOI 10.1109/IEEESTD.2014.6991462, December 2014,
              <https://doi.org/10.1109/IEEESTD.2014.6991462>.

   [IEEE-802.3]
              IEEE, "IEEE Standard for Ethernet", IEEE Std 802.3-2018,
              DOI 10.1109/IEEESTD.2018.8457469, August 2018,
              <https://doi.org/10.1109/IEEESTD.2018.8457469>.

   [RFC2544]  Bradner, S. and J. McQuaid, "Benchmarking Methodology for
              Network Interconnect Devices", RFC 2544,
              DOI 10.17487/RFC2544, March 1999,
              <https://www.rfc-editor.org/info/rfc2544>.

   [RFC2681]  Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
              Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681,
              September 1999, <https://www.rfc-editor.org/info/rfc2681>.

   [RFC3393]  Demichelis, C. and P. Chimento, "IP Packet Delay Variation
              Metric for IP Performance Metrics (IPPM)", RFC 3393,
              DOI 10.17487/RFC3393, November 2002,
              <https://www.rfc-editor.org/info/rfc3393>.

   [RFC5085]  Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual
              Circuit Connectivity Verification (VCCV): A Control
              Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085,
              December 2007, <https://www.rfc-editor.org/info/rfc5085>.

   [RFC6136]  Sajassi, A., Ed. and D. Mohan, Ed., "Layer 2 Virtual
              Private Network (L2VPN) Operations, Administration, and
              Maintenance (OAM) Requirements and Framework", RFC 6136,
              DOI 10.17487/RFC6136, March 2011,
              <https://www.rfc-editor.org/info/rfc6136>.

   [RFC6632]  Ersue, M., Ed. and B. Claise, "An Overview of the IETF
              Network Management Standards", RFC 6632,
              DOI 10.17487/RFC6632, June 2012,
              <https://www.rfc-editor.org/info/rfc6632>.

   [RFC6673]  Morton, A., "Round-Trip Packet Loss Metrics", RFC 6673,
              DOI 10.17487/RFC6673, August 2012,
              <https://www.rfc-editor.org/info/rfc6673>.

   [RFC7679]  Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
              Ed., "A One-Way Delay Metric for IP Performance Metrics
              (IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January
              2016, <https://www.rfc-editor.org/info/rfc7679>.

   [RFC7680]  Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
              Ed., "A One-Way Loss Metric for IP Performance Metrics
              (IPPM)", STD 82, RFC 7680, DOI 10.17487/RFC7680, January
              2016, <https://www.rfc-editor.org/info/rfc7680>.

   [Y.1731]   ITU-T, "Operation, administration and maintenance (OAM)
              functions and mechanisms for Ethernet-based networks",
              ITU-T Recommendation G.8013/Y.1731, August 2015.

Acknowledgements

   The authors would like to thank the following for their review of
   this work and their valuable comments: David Black, Martin Duke, Xiao
   Min, Gregory Mirsky, Zaheduzzaman Sarker, Dave Schinazi, John
   Scudder, Melinda Shore, Robert Wilton, Alexander Vainshtein, Stig
   Venaas, and √Čric Vyncke.

Authors' Addresses

   Samer Salam
   Cisco
   The Atrium Building, Floor 3
   Weygand St.
   Beirut
   Lebanon

   Email: ssalam@cisco.com


   Ali Sajassi
   Cisco
   170 West Tasman Drive
   San Jose, CA 95134
   United States of America

   Email: sajassi@cisco.com


   Sam Aldrin
   Google, Inc.
   1600 Amphitheatre Parkway
   Mountain View, CA 94043
   United States of America

   Email: aldrin.ietf@gmail.com


   John E. Drake
   Juniper Networks
   1194 N. Mathilda Ave.
   Sunnyvale, CA 94089
   United States of America

   Email: jdrake@juniper.net


   Donald E. Eastlake 3rd
   Futurewei Technologies
   2386 Panoramic Circle
   Apopka, FL 32703
   United States of America

   Phone: +1-508-333-2270
   Email: d3e3e3@gmail.com